This invention relates to a data cartridge appropriately usable as, for example, an external storage for backing up a hard disk used as a storage for a computer (CPU), and a data cartridge drive used for driving the data cartridge.
A data cartridge and a data cartridge drive for driving the loaded data cartridge have been used conventionally to back up a hard disk used as a storage of a computer. The data cartridge is formed like a flat box provided with a synthetic resin molded top cover attached on an aluminum base plate. Inside the cartridge, a magnetic tape is loaded with the magnetic tape being wound on and between a pair of tape reels (right and left). The data cartridge is further provided with a tape feeding mechanism comprising a driving roller, a pair of corner rollers (right and left), a driving belt for driving the magnetic tape wound on and fed among those three rollers, as well as other associated mechanisms.
On the other hand, inside the data cartridge drive is provided a driving mechanism comprising a magnetic head, a spindle motor, a capstan roller etc. When a data cartridge is loaded in the data cartridge drive, the magnetic tape comes in contact with the magnetic head, the capstan roller is pressed against the driving roller, and the motor drives the capstan roller to rotate, thereby rotating the driving roller so that the driving belt feeds the magnetic tape and the data is recorded on or reproduced from the magnetic tape by means of the magnetic head.
An aluminum base plate is used for such a data cartridge because of its excellent properties such as easiness to machine, light weight, and sufficient rigidity. However, aluminum is liable to suffer corrosion and corrosion of the aluminum has to be prevented by, for example, coating the surface of the base plate with an anodic oxide protection film as disclosed in Unexamined Published Japanese Patent Application No. 8-7969. In this disclosed patent, after the base plate material is machined into a flat plate, the surface of the flat plate is coated with an anodic oxide protection film and the external shape, holes, notches, etc. of the flat plate are punched (e.g., die-punching) so as to improve the accuracy of vertically fixing parts such as tape guide pins, on the base plate by press-fitting.
FIG. 1 shows a related art base plate 3 machined as explained in Unexamined Published Japanese Patent Application No. 8-7969. Either surface of the aluminum base plate 3 is coated with an anodic oxide protection film 300. This anodic oxide protection film 300 is a non-conductive film. After this protection film 300 is coated on the surfaces of the base plate 3, the external shape of the base plate is die-punched, so that only the external periphery end face 3c of the base plate, the inside end faces 3d of a pair of right and left positioning notches 31, and the inside end faces of other holes and notches that are die-punched become conductive portions of the base plate 3. The base plate 3 shown in FIG. 1 has been die-punched from below to upward, which causes shear drops 300a of the protection films 300 wrapping around the lower edges of the outer periphery end face 3c, the inside end face 3d of the notch 31, etc.
FIG. 1 also shows how to position a data cartridge loaded in the data cartridge drive. The positioning roller 84 is pressed against the lower edge 31a of the positioning notch 31 of the base plate 3 in the direction of arrow mark F (upper oblique portion) to lift the base plate 3 from the chassis 61 in the direction of arrow mark F, then the front end 3b of the base plate 3 is pressed against the vertical reference plane 79a of the cartridge loading guide 79 and the back-and-forth direction reference plane 83a of the cartridge loading stopper 83 in both directions of arrow marks F1 and F2 to position the data cartridge.
Data cartridges and data cartridge drives of this type employing the related art have had problems of accumulation of static electricity generated among the driving roller, corner rollers, driving belt, magnetic tape, etc. in the data cartridge while recording data on or regenerating data from the magnetic tape. The accumulated static electricity discharges to sometimes cause data write errors, data damages, etc. and various countermeasures have been taken to solve those problems. In other words, the accumulated static electricity is not easily eliminated since, as shown in FIG. 1, both upper and lower surfaces of the base plate 3 are coated with a non-conductive film such as a protection film 300 and only the outer periphery end face 3c, the inside end face 3d of the notch 31, etc. that are die-punched are conductive portions of the base plate 3, and the shear drop 300a of the non-conductive protection film 300 wrapping around the lower edge 31a prevents stable electrical contact of the base plate 3 to the grounded chassis 61 via the positioning roller 84 even if the roller 84 is pressed against the lower edge 31a of the notch 31 in the direction of arrow mark F for the purpose of grounding the base plate 3. In the related art, therefore, there has been no way other than using a shielding plate of the spindle motor or a circuit for shielding the base plate 3 and using such a shielding plate has expanded the size to cause increased weight and manufacturing cost of the devices.
Under such circumstances, it is an object of the present invention to provide a data cartridge and a data cartridge drive that prevent static electricity from being accumulated in the data cartridge.